Improvement in apparatus for roasting ores



H. P. HOWELL@ Apparatus for Roasting; Oras.

N'o.19s,767.' Pa medi;v .1v 1878.

NPTERS. PHOTO'LITHOGRAFHER. WASHINGTON. D C. l

UNITED STATESN PATENT OFFICE.

HENRYYF. HOWELL, or sAnNrA, ONTARIO, OANADA.

IIMPROVEMENT IN APPARATUS, FOR ROAS'TING ORES.

Specification forming part of Letters Patent No. 198,767, dated January l, 1878; application filed November 30, 1877.

To all whom #may concern Be it known that l, HENRY F. HOWELL, of Sarnia, in the county of Lambton, Province of Ontario, Canada, have invented certain Improvements in Apparatus for Treating Refractory Ores, of which the following is a specification:

My invention relates to apparatus and process for desulphurizing auriferous or other ores, especially arsenical pyrites, or `mispickel ores, in which the arsenicis volatilized at low temperatures; andconsists in means, substantially as hereinafter described, whereby I am enabled to. thoroughly and effectually carry olf the fumes or vapors of the arsenic which are'freed by the roasting of ,the charge? in the retort, and would otherwise be condensed in the mass of ore being treated. v

To effect these results, .my invention embraces, iirst, the employment of a heatedairchamber surrounding the retort, whereby the heat of the furnace is diverted from direct contactwith the exterior of the retort which contains the ores, and acts upon such retort only through the medium of the air-chamber, bywhich means the heat is uniformly distributed over the surface of the retort, and condensation in the ores of the vapors of the arsenic avoided.

Myinvention, secondly, embraces the method of assisting` to create, throughthe mass of ore held for treatment in the retort, a strong draft of hot air, for the purpose of materially accelerating the progress of the combustion and volatilization of the arsenic, sulphur, and other volatile elements, and the destructive distillation of the carbonaceous material embodied in the charge; such method consisting inintroducing into the air-supply pipe a `jet of steam under pressure, which produces a partial vacuum, andn compels the air to enter and ll it,

while at the same time a portion of the steam` enters the charge of ore.

Thirdly, my invention embraces the method of introducing a jet of steam into the escapepipe, through which the volatile products in the retort are carried off, (either to the condensing-chamber, if such products are to be utilized, or into the atmospherepth'e condensation of this jet of steam having the'effect of v producing a partial vacuum above the retort,

and inducing through the charge a powerful draft of hot air from the air chamber or pipes below, the same being as hereinafter described. For a full comprehension of the nature and operation of my improvements, reference must be .had to the accompanying drawings, in which-.A

Figure l is a sectional elevation, and Fig. 2 a vertical section, of a retort embodying my improvement. i ln such drawings, A represents a retort, preferably circular in form, and of a size varying with the desired capacity for treatment, but usually being from three to five feet in diameter, and about two feet in depth, such retort being disposed within a similarly-shaped shell or casing, B, of somewhat greater depth and diameter, and being formed with a concentric flange, C, which surrounds its mouth, and rests upon the upper edge of the said casing B. 1 1 The casing B is partially built up in brick- Work, and supported therein in any suitable manner 5 and its bottom constitutes the top of the furnace, which is shown at B', the grate of such furnace being shown at C", and the 1 `ash-pit at D, while b and d are, respectively,

the fuel-supply door and ash-pit door, and E the iiue for carrying off the smoke andwaste products of combustion from the furnace.

The' space or chamber G, intervening between the side walls of the retort A and case B,may be aboutthree-quarters of an inch, and between the bottoms of the two of about three inches; and the bottom ofthe retort Ais perforated with small holes, of such size and in such number as practice may determine best. The top of the retort A is covered by a frusto-conical hood, K,which is sealed at bottom to the top of the retort by a sand joint, Y

while L is a large pipe risingV from the top of the hood, for the purpose of carrying off the fumes of -the retort, such pipe being led to the open air, or, in instances where the arsenious or other volatile products are to be utilized, to any suitable condensing flue or receiver; and itis well that a slidingjoint exist in the pipe immediately above the hood, in order that the latter may be readily removed in charging or emptying the retort. y Y p K in the accompanying drawings represents a pipe, provided with a stop-cock, af, at any suitable point, this pipe lK communicating at one end with the interior of the pipe L, and at the other end with a steam-generator, or other source of steam-supply, or with any other device for producing a partial vacuum. By admitting a blast of steam under pressure through the pipe K into the escape-flue L, a partial vacuum is created in the hood over the charge of ore in the retort, thus not only causing the vapors of arsenic and sulphur in such charge to be rapidly eliminated and carried off into the discharge-flue, but to greatly expedite the passage of air and steam from the chamber below through the mass of ore.

M in the drawings represents a pipe, provided with a stop-cock at any suitable point, and passing at one end throughv the brickworli and air-chamber B, and communicating with the interior of the retort A, and at the other end with an air-forcin g machine or other source of supply under pressure, While N is a steampipe communicating at one end with the interior of the air-pipe M, and at the other with a steam-generator, and provided with a stop-cock, n, and preferably with a petcoek, the latter being to carry off condense-water, and prevent its getting access to the chamber G.

p By' admitting a jet of steam into the pipe M such steam creates a partial vacuum, which compels a rush of air to fill it, and thus causes a powerful draft, while a portion ofthe steam passes with the air into the charge o f ore in the retort.

l By this method the combined steam and air can be driven into the lower part of the re tort and through the mass of ore in any proportion, and this proportion may be directlyv controlled by the attendant. This is of especial importance to prevent slagging of the -v sulphuret.

By the employment of the hot-air chamber VGr, surrounding the retort, I divert the heat of the furnace from direct contact with any one restricted part of the retort, and compel such heat to distribute itself generally about such retort in the form of hot air in such chamber; and by, this means, as before stated, I avoid the condensation in the mass of ore of the arsenious or other vapors, and compel such vapors to pass to the escape-hue, and this eifect is aided by the hood K.

i A I will now describe, briefly, the operation of the apparatus before described, and the process which it carries out.

The mass of ore to be treated is first ground topa powder of the requisite fmeness; and as it is essential that the ore thus prepared shall contain about twenty-vevper cent. of neutral matter to prevent slaggin g, this matter should be added, if the ore is of such 'nature that it does not possess it naturally. l

To the mass I now add about its own .bulk of some carbonaceous material, such as browncoal, tan-bark, peat, die., 'or analogous substances, and thoroughly incorporate the two,

and then moisten the whole with salt and water, but not to such an extent that the latter shall escape from the mass.

The use of salt and water maybe dispensed with; but it has been found very serviceable, not only in my own experiments, but for many years in Germany, where it has been employed extensively; and the action of the salt leaves the metal clean and in favorable state for' amalgamation.

I now place upon the perforated bottom of the retort A a quantity of straw or other carbonaceous matter, and then fill the retort with the mass adulterated and moistened, as before explained, the straw serving to prevent escape of the ore through the perforations of the bottom.

Thehood K, which hadbeen previouslyraised or removed, is now lowered to place into its sand joint, the re started in the furnace, and the retort heated to the proper degree, when the cock is opened, and air under pressure is driven through the pipe M into the air-chamber Gr, surrounding the retort, in which it becomes heated to a temperature of from 5000 to 600O Fahrenheit. The first effect of the heat upon the charge in the retort is to dry up the moisture therein, which having been accomplished, the hot air ignites the sulphur in the charge, and the sulphur, in its turn, ignites the brown-coal or other carbonaceous element, and the combustion of the two thoroughly effects the volatilization of the arsenic, sulphur, or other matters capable of volatili'zation.

Certain advantageous effects are also produced by the decomposition of water in the steam, while the combustion of the brown-coal or its substitute leaves the ore in a porous state, highly favorable for the escape of the vaporized matters.

The destruction of the combustible matter continues until it ceases for want of fuel, when the operation is completed, and theretort may be emptied.

Although I have described a method or process which consists, in part, of the employment of la carbonaceous material mixed with the charge of .ore for purposes stated, and again, in part, of the employment of salt or salt and water, wherewith to moisten the mass of ore, I do not claim as of my own invention such steps in the process of desulphurizing ores, but only when they are carried on in my retort.

rlhe use of carbonaceous material as an admixture of the ore, and of salt or salt and water, is not only described and claimed in Letters Patent of the United States numbered 186,654, and issued on the 23d day of January, 1877, to Z. A. Willard, of Boston, Massachusetts, but has existed in Germany for many years, and is fully described in a work entitled A Practical Treatise on Metallurgy, adapted from the last German edition of Prof. Kerls Metallurgy, by William Crookes, F. B. S., &c., and Ernst Rhrig, Ph. D., M. E., 1868. In this work, on pages 211, 364, and 365, Augustins process is explained as employing-salt or salt and Water. On page 366 the -use of steam in the roasting process is alluded to, .While on page 367 it is stated that Roeszner and Patera have found a mixture of saltwater and chlorine Water to be au excellent reagent for extracting gold and silver at the `saine time, ,While on the sameQpage it is stated that Markus roasts in a mufflkeljwith the use of a steam-jet, and so on through the Work. On pages 383, 384, and l385 of"said Workthe use y of carbonaceous material incorporatedwith the mass for purposes stated is explained. i Therefore I do not `claim as my invention the incorporation of acarbonaceous material With the charge, nor the use of salt and salt and Water therewith. y y t I do not conne myself to the use of the steam-jet pipe, arranged as shown, for indue` ing a partial vacuum above the mass in the retort, although it is a very effectual and inexpensive means of `producing it, as a vacuumpump of proper construction, or other devices, may be employed for the purpose. N or do I restrict myself to the precise construction of the retort A and casing B as a means of di i verting the direct heat ofthe furnace from the said retort, and providing an intermediateairchamber, as this construction may Avary Without departing from the spirit andgistof my invention in thisrespect. y y y I claimy u y `l. The combinationwith the retort, provided with anopening above for escape of the fumes; of an air-chamber surrounding the bottom and sides of the retort, and a draft-conduit communicating with said chamber, the combination beingand acting asset forth. y t

\ 2. .The combination of theretort, the escape opening or ue above the same, and. a'draftaccelerator for producing a partial vacuum in the retort and increasing the draft through the same, `With an airchamber surrounding the` bottom and sides of the retort, and a draftconduit communicating with said chamber, substantially as set forth. t

3. The combination of the retort Afilue L, i t pipe K', air chamber or jacket B, and air andi: steam pipes M N," arranged for joint operation#` as shown and described. y y A HENRY F. HOWELL. Witnesses:` t i Y i i i FRED. GURTIs,

LoUIs A. CURTIS.` 

